112 "Report of the Magnetic Survey of India. [No. 2, 



stations (deduced from simultaneous observations at intermediate 

 places), our present results may be altered in some degree. 



Temperature of the air and of the groimd. 



4th. The Meteorological observations of the dry and wet bulb 

 Thermometer, of the temperature of the ground from the surface 

 to a depth of five or six meters, of the temperature of rivers, &c. 

 have been regularly made in connection with the Barometric observe 

 atioos ; a regular series of observations being made at all the stations 

 where we halted for some time. "We found that the moisture of 

 the atmosphere considerably decreased as we advanced from the 

 southern branches of the Himalayas northwards to the high valleys. 

 In Thibet, the dryness of the atmosphere was constantly very great, 

 It is also worth remark that in Thibet, daring the warmest months 

 of the year, in July and August, the temperature of the air is 

 sometimes very warm, rising in the shade at elevations of 13,000 

 and 14,000 E. I\ to from 22° to 25° (centigrade). The temperature 

 of the surface of the ground exposed to the sun rises to 45° centi- 

 grade. 



The variations of temperature are, at the same time, very great, 

 and sudden clouds, which prevent for a time the heating of the 

 soil by the sun, produce, after a short time, a great decrease in the 

 temperature of the air, amounting to 10° and 12° cent. Passing 

 clouds, sending down suddenly a light fall of rain, or more often of 

 fine-grained snow, are also of very common occurrence, both in the 

 Sutlej valley and on the Passes. 



5th. The rainy season extends, though with much diminished 

 force, up to the highest valleys along the southern water-shed of 

 the Himalayas. It begins later and ends earlier than in the outer 

 ranges, and on many days the threatening clouds travel up from the 

 southward to the higher valleys, without producing any sensible fall 

 of rain. The rainy season cannot be said to extend properly speak- 

 ing across the Himalayas into the basin of the Sutlej. The regular 

 succession of the dry and rainy seasons of India is unknown there, 

 and, from very good information which we obtained, there is no 

 month of the year which can be considered free from rain. But 

 nevertheless the influence of the Indian rainy season is still felt in 



